Create a surreal and imaginative scene of a massive tortoise swimming gracefully

Create a surreal and imaginative scene of a massive tortoise swimming gracefully in the ocean. The top half of its shell is transformed into a small city, where modern architecture blends with nature. The city features sleek buildings, lush palm trees, patches of greenery, and a sandy beach along the edges. Prominently placed on the cityscape is a water purifier tank, symbolizing the source of clean water for the inhabitants. The water surrounding the tortoise is crystal clear, allowing a full view of its majestic body submerged beneath the surface. The underwater scene should include realistic reflections of the city above and the serene, calm waters. The sky overhead is a bright, clear blue, dotted with fluffy white clouds, enhancing the dreamlike quality of the scene.